You will need to do a hard factory reset.
• First, switch your tablet off.
• Then, power the tablet back up by holding down the volume (either + or - ) and power buttons simultaneously.
• Continue holding the volume button until the screen says "Booting tablet in recovery mode."
• This will give you a picture of an Android.
• Tap the android, and you will be given a screen with several options.
• Move between the options with the + and -, and select with the power button.
• Go to the option for Factory Data Reset and select it.
• Scroll down to `the Yes, and then the tablet will erase its memory back to factory settings.
• Once it has completed, select Reboot Tablet Normally.